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Slice flank steak drizzled with glazed on pate with bok choy.
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Sous Vide Flank Steak

Tender, juicy sous vide flank steak with a flavorful balsamic marinade and glaze. Includes easy time and temperature options for perfect results every time.
Prep Time10 minutes
Cook Time2 hours
Total Time2 hours 10 minutes
Course: Main Course
Cuisine: American
Servings (change as needed): 4
Author: Cheryl Avrich
US Measures - Metric

Ingredients

  • 1 1/4 pounds flank steak, Note 1
  • kosher salt and black pepper

Marinade and Glaze

  • 3 tablespoons olive oil
  • 1/4 cup balsamic vinegar, Note 2 (good quality)
  • 1 tablespoon grainy old fashioned mustard (or Dijon)
  • 1/4 teaspoon garlic powder
  • 1 teaspoon dried rosemary (or 2 tsp fresh, chopped)
  • 1 teaspoon dried thyme (or 3 tsp fresh, chopped)
US Measures - Metric

Instructions

  • HEAT THE WATER IN SOUS VIDE MACHINE: Heat the sous vide water bath to 132°F (56°C) for medium-rare, or to your preferred temperature (Note 3).
  • MAKE MARINADE/GLAZE: In a small saucepan, combine olive oil, balsamic vinegar, mustard, garlic powder, rosemary, and thyme. Pour half the mixture into a large zip-top bag or container for marinating the steak. Reserve the remaining half in the saucepan for the glaze.
  • MARINATE FLANK STEAK: Season the flank steak with salt and pepper. Poke it all over with a small sharp knife to let the marinade seep in. Add it to the marinade and coat well. Marinate for 4-6 hours or overnight.
  • SEAL FLANK IN BAG: Remove the steak from the marinade and lightly pat off excess moisture.one vacuum seal bag. Cut flank steak in half if too large for bag. Place the steak in a sous vide bag and seal using your preferred method (Note 4 for vacuum seal and water displacement instructions).
  • SOUS VIDE FLANK STEAK: Cook the steak in the water bath for:
    ° 1 1/2 to 2 hours for thinner steaks (about 1/2 inch thick) or
    ° 2 to 4 hours for thicker steaks (I often choose 3 - 3.5 hours)
  • MAKE GLAZE: While flank steak is cooking, bring reserved marinade in saucepan to a boil, lower heat to medium and cook until reduced until slightly thickened and glossy enough to coat the back of a spoon.
  • SEAR AND SERVE: Remove steak from the bag and pat very dry with paper towels. Lightly oil and season again with salt and pepper. Grill over high heat or sear in a very hot skillet with a tsp oil for about 1 minute per side until browned. Slice thinly against the grain and drizzle with glaze before serving.

Notes

  1. Flank steak: Prime, Choice, AAA, or Angus cuts will be the most tender, but sous vide will make less expensive cuts tender with a little more cook time.
  2. Balsamic vinegar: This recipe is best with a high-quality balsamic. Lesser quality can be too acidic (you would need to add a touch of sugar and only marinate 6 hours or the meat can break down and get mushy. Then pat dry before sous vide cooking). Substitute with red wine vinegar and a bit of sugar or maple syrup.
  3. Time and Temperature options:
    Desired Doneness Temperature Texture and Color
    Rare 125-129°F (52-54°C) Very soft texture with a red center
    Medium-rare (recommended) 130-135°F (54-57°C) Tender and juicy with a warm pink center
    Medium 136-140°F (58-60°C) Firmer texture with a pink center
    Medium-well 145-150°F (63-66°C) Mostly firm with just a hint of pink
    Cook for 2-4 hours depending on thickness and your preferred texture. For thinner flank steaks (about 1/2 inch/1.3 cm thick), reduce cook time to 1 1/2 to 2 hours.
  4. Bag sealing options
    • Vacuum seal: Fold over a flap on 1 (or 2) vacuum seal bags. Place flank steak (patted dry) into bag. Unfold flap and seal with vacuum sealer.
    • Water displacement method: Place meat in a freezer-grade ziploc bag. Lower bag into waterbath, letting the water pressure push the air out of the bag. Seal the bag just above the water line before fully submerging it.
  5. Make-ahead: You can sous vide the flank steak and prepare the glaze up to a few days ahead. Chill the sealed bag in an ice bath for 20-30 minutes before refrigerating. When ready to serve, grill or sear the steak for 1-2 minutes per side and drizzle with the glaze.
  6. Freezing/reheating: After sous vide cooking, chill the sealed bag in an ice bath for 20-30 minutes, then freeze. Thaw overnight in the refrigerator if frozen. Reheat in a sous vide bath at the original cooking temperature for 30-45 minutes, then quickly sear or grill before serving.
 
Nutrition values are estimates. 
 
 
Serving: 0g | Calories: 305kcal | Carbohydrates: 3g | Protein: 31g | Fat: 18g | Saturated Fat: 4g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 11g | Cholesterol: 85mg | Sodium: 411mg | Potassium: 512mg | Fiber: 0.3g | Sugar: 2g | Vitamin A: 13IU | Vitamin C: 0.2mg | Calcium: 42mg | Iron: 3mg